Coil



Patented Dec. 4, 1928.

UNITED STATES 1,693,837 PATENT OFFICE.

HIRAM D. GURRIER, OF CHICAGO, ILLINOIS, .ASSIGNOR TO KELLOGG SWITCHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

COIL.

Application filed October 25, 1924. Serial No. 745,750.

My invention relates to coils or transformers, and has to do more particularly with transformers of the air core type which are provided with a variable primary and secondary and which in the wireless or radio art are used in circuits of radio receiving sets.

In transformers of the above type, the primary and secondary each comprise a plurality of convolutions wound upon a tube support of a suitable insulating material. It has been found that large losses occur, due to leakage of the coils, owing to the fact that the convolutions of the wire are in contact with their supporting member and with each other and one of the features of my invention is the provision of an improved coil in which the supporting means presents only a small contacting surface for each convolution of the winding and in which the convolutions are in spaced relation with each other to thus reduce this leakage to a minimum.

Another feature of my invention is the provision of an improved coil construction in which tiers of insulating strips are built up to form arms which are equally spaced apart,

and at rightangles to each other, and in which the strips are provided with means for equally spacing the convolutions of the winding and in which the strips also equally space the layers of convolutions.

- Another feature of my invention is the provision of parallel slots in the two faces of the strips which register as the strips are superimposed one above the other to form the arms or spider for supporting the convolutions of the winding. tom face of the strips which register when stacked, form means for maintaining the convolutions of the layers in spaced relation with each other and prevent any movement of the individual convolutions.

Another feature of my invention is the provision of orifices in the strips which are adapted to receive the terminalcnds of the taps of the talgu ed primary and secondary to permit these terminal ends to be led from the same side of the transformer face for convenience in connecting these terminal leads with apparatus in the circuit with which the transformer is associated. The features ust mentioned, as well as others relating to details of construction and combination of parts will be hereinafter more particularly pointed I claims.

The slots in the top and bot- F or a more complete understanding of my invention reference may be had to the accompanying drawing in which the reference characters in the several views denote like parts and in. which Fig. 1 is a front elevation of the transformer of my invention;

Fig. 2 is a left side'view of Fig. 1;

Fig. 3 is a top view of Fig. 1;

Fig. 4 is a sectional view along the line 4-4 of Fig. 1;

Fig. 5 is a perspective viewof the supporting core of the transformer, and

Fig. 6 is a perspective View of one of the separator strips for supporting the winding of the transformer.

Referring now more in detail to my invention as illustrated the transformer of my invention comprises a plurality of convolusions T of wire wound in layers L, in which each adjacent turn T of a layer L is equally spaced apart and each of the layers L of convolutions of the winding are also separated an equal distance. To accomplish this I have produced a novel method of construction in which the transformer comprises a core 2 of suitable insulating material, such as hard rubber, the said core 2 being square in shape with its corners chamfered to present angular faces3, 4,5 and 6 for purposes as will presently be described.

The winding is built up of a plurality of layers L of convolutions T, and to equally space adjacent turns in a layer and space the successive layers L, I provide separator strips 7, and to construct a transformer of this type a suitable fixture is provided. The fixture is of suitable construction comprising two sec tions, each of which is provided with a body portion and four integrally formed extending arms at right angles to each other. The sections when. placed together inmatched relat ion to clamp the core 2 between the body portions of the fixture sections also places the extending arm in matched relation to form channels of a size'to permit the insertion of the rectangular separator strips 7. The separator strips 7, one of which is illustrated in perspective in Fig. 6 is made of a rectangular strip of insulating material, such as hard rubber, the top face 8 of which is provided with parallel slots 9,. 10 and 11 and the bottom face 12 of which is also provided with parallel slots 13, 14 and 15.

The assembly fixture, as before described,

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clamps the core 2 in position, and with the core 2 thus clamped a separator strip '7, as illustrated, positioned in the channel of an arm, of the tixture with its bottom face 12 rest-- ing against the angular face 3 of the core The inside terminal of the winding is secured to the strip T by threading its end through an orifice 30 in the strip 7 to secure the same in position and the wire 20 is now laid in the slot 9 of the strip 7. With the strip 7 in position vith the wire 20 in the slot 9, the fixture now turned to present the other three arms of the fixture in succ ion to permit sepa 'ator strips 7 to he positioned in the channels of the arms with their bottom faces 12 resting against th angular faces '12, 5, and (3 of the core 2. The wire 20 is laid in the slots 9 of these three strips 7 that are placed in succession in the remaining three arms of the ti ture, and the continued turning of the fixture will permitthe wire 20 to he laid in the slots 10 and 11 of the four strips 7, which rest againstv the respective angular faces 3, l, and

(5 of the core The. first layer L, which comprises three turns or convolutions T is thus supported on the core 2 the said turns or convoli ions 14 1iing in the slots 9, and 11 of the four strips 7. To place the next layer L of convolntions on the core a a strip 7 is positioned in the channel of the arm of the fixture that rece' 'ed the strip 7, to which the inner terminal of the winding: is se ured, the second strip T resting; in position with its bottom face 12 resting against the face 8 of the tin i'p T. The slots 13, let and 1? in the bottom face 12 of this second strip '7 register with the slots 9 10, and 11 of the strip 7 which received t2: convolutions of the first layer L, {1115 t slots in the respective faces 8 and 12 of in strips 7 are so shaped and of such a e receive the wire and to permit a portion of its circumferential face to project above the face 8 of the first strips 7. Now when the second strips 7 are placed in position with their hottom faces 12 resting ag inst the faces 8 in the strips T which are now supporting the convoutions of the first layer L, the proiccting portions of these convolinions extend in the slots 13. 1% and 15 of the strips '7 resting in position hetween the two strips 7 to maintain the individual convolntions T of the layers L in spaced relation with each other and at the same time prevent any movement of the convolutions. Vith the second strip 7 in position as just described the wire is laid in the slot 11 of the second strip 7 and the fixture is then turned to present the other three arms of the fixture in succession to permit the other three strips T to be positioned in the channels with their bottom faces 12 resting; asra' 1st the faces 8 of the stri T arc-ad in posi The slots 13, ll and i ,1 the respective faces stcr with the slot 9,

of these strips '7 rr ri 10 and 11 of the first rips 7 to receive prothe recuircd numher of turns T which are to he placed upon the supporting core 2 and with the required number of tar] has supported the outside end. of the winding threaded through one of the orifices in the strip 7 of the last tier, thus securing it against movenicnt.

'lhe ahoveniethod of oonstr iction in which the four arms a, I) c and (Z are built up of superimposed strips 7 will form a spider in which the arms a and Z2 extend out-ward from the srpportir5 core at right angles to the outwardly extending arms 0 and (Z. The wire 20 it placed in the slots of the strips 7 in layers L is held taut hy suitalile means durinn" the winding operation of the transformer, to produce a clamping effect upon each strip T, as it is superimposed. on a strip 7 already in position, thus each arm a. l, 0 and (I is selfsupporting, each being huiltup of tiers of strips 7, and the late 'al movement of the strips 7 in relation to each other is prevented hy meant of the pressure exerted by the convolutious T of each layer upon its supporting strips 7 and this pressure exerted by the convolutitnis T of each layer L also prevents tilt ing or inovei'i'icnt of the arms (a, 7), c and (Z as a whole, on the core 2. 'ith the convolutions of the winding of each layer L resting in slots Sh 10 and 11 of its supporting strips 7 and the slots 13. ll and 15 of the next tier of strips 7, it impo; hle to displace the convolut-ions from their fixed spaced relation with ach other. as each succeeding strip 7 as it is placed ahove the other prevents any movement of the ndividual convolution of a layen The clampingetfcct oi the strips 7 due to the pressure exerted by the convolutions of each layer causes the strips to clamp the wire in the ori lice formed hy the slots 9. 10 and 1.1 in the face 8 of the strip T and the slots 13, 1:1: and 15 in the bottom face 1:? of the next strip ahoic to prevent the individual convolution from becoming loose, and also prevents the stri Y5 from moving relative to each other.

The. transformer of my invention as illustra ed comprises a variahlc primal-f and a uhlc sccontairy. The windings are providcd with a predetermined number of taps wiiich are soldered at the points 36 of a coni' i'ol fi'il i-iuitahle orii" 30 in the strips,

1 ihhort the rs L. l he transformer is also provided with a predete mined numswitch provided.

"These terminal leads 37 and 35 are now se- I cured to switch points of suitable variable switches for varying the inductance of the primary and secondary of the transformer.

Through the agency of these two variable switches associated with tne tapped primary and secondary, the inductance of either one maybe varied for purposes as are readily understood in the art. I

From the foregoing it will be noted that every other layer of coil is tapped from the same side of the coil; and that the other layers of the coil are tapped from the opposite side of the coil, thus providing taps for each three turns or for each layer of the coil. This method of tapping the coil is made necessary from the fact that the coil is wound back and forth. If it is desired the coil may be used as an auto-transformer and only one variable By tapping the coilin this method each tap lead thereof is threaded through strip 7 at least once, thereby preventing the soldered tap from pulling loose from the coil, the one set of taps being threaded through the blocks 7 once and the alternate set of taps being threaded through the blocks 7 twice so that all taps extend from the same side of the coil.

\Vhile I have illustrated the strips 7 with slots to permit each layer of convolutions to have three turns, I do not wish to be limited to the exact number of slot-s, as a larger strip 7 may be employed with a greater number of slots to accommodate a greater number of convolutions per layer to increase the number of turns without departing from the spirit of the invention. It may also be seen that I have constructed a coil which is substantially built, and which may be handled without deranging the winding or shifting the arms of the spider, as a whole, due to the binding effect of the convolutions on the individual strips 7, of the arms a, Z), c and d. which are built up of a plurality of strips 7. By this method of construction, I also eliminate the large leakage or drainage of the prior coils as the point of support of the convolutions is reduced to a minimum in the transformer of my invention, whereas, in prior coils, the turns ofwire are in direct contact with the supporting member or tube and with each other, throughout the entire length thereof.

While I have described a particular form of coil, it is to be understood that changes and modifications will readily suggest themselves to those skilled in the art, and I therefore do not wish to be limited to the exact structure as shown, but aim to cover all such changes and modifications as come within the spirit and scope of the appended claims.

Having described my invention what I claim as new and desire to secure by Letters Patent is:

1. A coil of the character described comprising spaced convolutions of wire wound in spaced layers, a core provided with diametrically opposite angular faces, strips superimposed upon said diametrically opposite angular faces of said core to form arms for supporting said convolutions, certain of said strips having longitudinal orifices for supporting taps from said convolutions of wire, slots in both faces of said superimposed strips in matched relation forming means for maintaining said convolutions in spaced relation, said convolutions producing a binding effect to make said superimposed strips which form said arms selfsustaining.

2. A coil of the character described comprising spaced convolutions of wire wound in spaced layers, a core provided wit-h diametrically opposite angular faces, strips superimposed upon said diametrically opposite angular faces of said core to form arms for supporting said convolutions, certain of said strips having longitudinal orifices for sup porting taps from said convolutions of wire, slots in both faces of said superimposed strips in matched relation to form means for encompassing portions of said winding for maintaining said convolutions in spaced relation. said convolutions producing a binding effect to make said superimposed strips which form said arms self-sustaining.

3. A coil of the character described comprising spaced convolutions of wire wound in spaced layers, a core provided with diametrically opposite angular faces, strips superimposed upon said diametrically opposite angular faces of said core to form arms for supporting said convolutions, certain of said strips having longitudinal orifices for supporting taps from said convolutions of wire, .slots in both faces of said strips in matched relation when superimposed to form orifices which encompass and contact with the wire for substantially short distances for maintaining said convolutions in spaced relation, said convolutions producing a binding effect to make said superimposed strips which form said arms self-sustaining.

7 4. A coil of the character described comprising spaced convolutions of wire wound in spaced layers, a core provided with diametrically opposite angular faces, strips superimposed upon said diametrically opposite angular faces on said core to form arms for supporting said convolutions, certain of said strips having longitudinal oritices for supporting taps trom said convol itions of wire, slots in both faces of said strips in matched relation when superimposed to form orifices which CIlCOlllPttSS and contact with the wire for substantially short distances, said matched slots in said strips forming means for maint-aininp said convolutions in spaced relation, said wire forming bindingmeans for holding the coil in shape.

5. A coil of the character d frihed com prising spaced eonrolutions 01 wire wound in spaced layers, a core pro *ided with diametrially opposite ang ular faces, strips superimposed upon said diametrically opposite angular faces of said core to form arms for supporting said convolutions. and means in adjacent strips for main lining said conrolutions in spaced relation, said con- Volutions forming binding means for mairtaining said superimosed strips which form said arms sel't-sastainin ii; position, taps leading; from predetermined layers of raid coil, said taps leading from through longitudinal orifices and extending from the same or said c El.

6. A device of the cha 'acter described including a core provided with angular faces, strips superimposed upon saii an lar faces to form arms, slots n the 01 t strips, a winding supper-ten i slots, tap leading from said winding, certain of said strips havinglongitudinal orifices for suiporting said taps from said winding, s 'd winding extending into the slots of adja ent strips for maii'itainingsaid strips in liner 1 lation to each other and forming binding means to maize said superimposed srrios which form said arms self-sustaining.

7. A coil of the character described includit convolutious of wire, said c nroln ions hem sf ui'Sa'al from each other and said are: hon spaced from each other. tllfilwltlllg mean tor said conrolntions of wire, a core upon which said supporting means are poftioned to form 1 the con- \(BllliiOllS ot (ire extending: thronga demo sions in adjacent supportinv' me -t to prevent the movement of one supporting means relative to its adjacent supporting: means, uaid conrolutions; ot' aii'! layers forming dii means to nialte said 5-3li] )th"-!'i'l1if in' selhsustainii certain oi said supporting means liaiir pairs of longitudinal orifices, taps tors it ex ltlillf-Z through said orifices in ai -ting means, certa n o't ."ih taps extend e Slltl oritices and ot i no n to nialie said iuppoi rim Q means sel t-sustamno, taps for the diil' erent layers of the e2 tain of said support in; means liili'illfj pairs t ojl i J 'itudinal orifices. part of the taps living c' i "wed on, one f-Iltlt} of the coil and or endi 'ou sih one ol said pair of longitudinal orilicea and the other taps heing connected on the other side of the e ill and extending through ioth of said pair of longitudinal orifices in the sugportingr in MRS so that all taps are hroue'ht out on the same side of the coil.

Signed by me at Chicago. county of Cook. and State oi, Illinois, this 23d day o'lf October, 192%.

HIRAM D- CURRIER.

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